Heat generating elements such as power modules for high pressure resistance and large current to be mounted in a hybrid vehicle, an electric vehicle, and others generate a large self-heating value or amount during operation of semiconductor elements. Accordingly, such a heat generating element has to include a cooling structure having high heat dissipation performance. That is, a heat exchanger is required to efficiently dissipate heat from the heat generating element.
In one of the heat exchangers, adjacent fins are placed in offset arrangement (with displacement of peaks and roots between adjacent fins) (see Patent Document 1). In this heat exchanger, the fins are offset arranged, causing a turbulent flow of coolant (cooling medium) to avoid the generation of a boundary layer in the coolant, so that a heat transfer coefficient between the fins and the coolant is improved.
For the above heat exchanger, particularly, it is necessary to accurately position the fins in place. If an offset amount of the fins deviates from a design value, the boundary layer occurs in the coolant. This results in a disadvantage that could not improve the heat transfer coefficient between the fins and the coolant.
It is therefore necessary to hold each fin in a predetermined position, i.e., position each fin in place. In one heat exchanger, such a fin positioning mechanism is provided for example by a protrusion and a recess each formed in a holding member that holds the fins (see Patent Document 2).